The present invention relates generally to laser drilling, and more particularly, to a workpiece holder having multiple recesses to better support a flimsy workpiece during a laser drilling operation.
Material ablation by pulsed light sources has been studied since the invention of the laser. Reports in 1982 of polymers having been etched by ultraviolet (UV) excimer laser radiation stimulated widespread investigations of the process for micromachining. Since then, scientific and industrial research in this field has proliferatedxe2x80x94mostly spurred by the remarkably small features that can be drilled, milled, and replicated through the use of lasers.
Ultrafast lasers generate intense laser pulses with durations from roughly 10xe2x88x9211 seconds (10 picoseconds) to 10xe2x88x9214 seconds (10 femtoseconds). Short pulse lasers generate intense laser pulses with durations from roughly 10xe2x88x9210 seconds (100 picoseconds) to 10xe2x88x9211 seconds (10 picoseconds). A wide variety of potential applications for ultrafast and short pulse lasers in medicine, chemistry, and communications are being developed and implemented. These lasers are also a useful tool for milling or drilling holes in a wide range of materials. Hole sizes as small as a few microns, even sub-microns, can readily be drilled. High aspect ratio holes can be drilled in various applications, such as cooling channels in turbine blades, nozzles in ink-jet printers, or holes in printed circuit boards.
Optical parallel processing of laser-milled holes is key to increasing the throughput and profitability of laser micromachining. Beamsplitting devices such as diffractive optical elements are currently used in laser micromachining to divide a single beam into multiple beams to allow for parallel processing of the workpiece (i.e., the material to be drilled).
In order to perform precision laser drilling in a parallel process system, the workpiece surface must remain in the focal plane of the laser drilling system (the plane in which the laser beams are focused) throughout the laser drilling process to enable the beams to drill workpiece geometries meeting precise specifications. However, the use of thin, flimsy workpieces (workpieces that bend and move outside the focal plane of the drilling laser beam when the workpiece is impacted with the beam), which are required in applications such as inkjet nozzles, poses a challenge because the workpiece deforms during drilling and moves outside the laser system""s focal plane. This results in poor quality laser-drilled holes and an inability to meet required product specifications. What is needed is a way to improve the support of a flimsy workpiece in a parallel laser drilling system.
In accordance with the present invention, an improved workpiece holder is provided for use in a laser drilling system. The workpiece holder includes: a body having at least one planar support surface adapted to support a workpiece; a plurality of recesses formed in the planar support surface; at least one groove formed in the planar support surface; and a vacuum passage extending through the body of the holder. In one embodiment, the plurality of recesses are configured to align with the drilling pattern of the laser drilling system.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.